I haven't been to Monad Shoal, Mapalpascua is on my bucket list though. Sounds like I need to get there soon!!!
I agree, 1st and foremost Instructors, DM's and dive guides should be the first line of training for divers on how to properly dive the site, and divers need to learn and practice diving responsibly with neutral bouyancy.
That being said, and I hope this doesn't sound stupid, but in the broken rubble can you build some dead coral hedge or cement structures, that divers could then attach a reef hook to (like the one started at Manta Sandy in R4)? Properly used with a little air added they can get off the bottom, while still letting the Thresher control the experience? Or sink some steel rods with eye hooks into the rubble and attach lines between so divers can attach a john line to it? Either of these would allow use from either side depending on the current or location of the Thresher.
I realize this doesn't fix the problem of bad diver bouyancy or behaviour, but...